Lens with multi-convex meniscus wall

ABSTRACT

The present invention relates generally to an arcuate liquid meniscus lens with a meniscus wall. Some specific embodiments include a liquid meniscus lens with a meniscus wall essentially in the shape of multiple segments of a torus convex toward the optical axis. Embodiments may also include a lens of suitable size and shape for inclusion in a contact lens.

RELATED APPLICATIONS

This application claims priority to Provisional U.S. Patent ApplicationSer. No. 61/380,745, filed on Sep. 8, 2010.

FIELD OF USE

The present invention relates generally to a liquid meniscus lens, morespecifically, it includes an arcuate liquid meniscus lens with ameniscus wall including multiple convex segments.

BACKGROUND

Liquid meniscus lenses have been known in various industries. Asdiscussed more fully below with reference to FIGS. 1A and 1B, knownliquid meniscus lenses were engineered in cylindrical shapes with aperimeter surface formed by points at a fixed distance from an axiswhich is a straight line. Known liquid meniscus lenses have been limitedto designs with a first interior surface generally parallel to a secondinterior surface and each perpendicular to a cylindrical axis. Knownexamples of the use of liquid meniscus lenses include devices such aselectronic cameras.

Traditionally, an ophthalmic device, such as a contact lens and anintraocular lens included a biocompatible device with a corrective,cosmetic or therapeutic quality. A contact lens, for example, canprovide one or more of: vision correcting functionality; cosmeticenhancement; and therapeutic effects. Each function is provided by aphysical characteristic of the lens. A design incorporating a refractivequality into a lens can provide a vision corrective function. A pigmentincorporated into the lens can provide a cosmetic enhancement. An activeagent incorporated into a lens can provide a therapeutic functionality.

More recently, electronic components have been incorporated into acontact lens. Some components can include semiconductor devices.However, physical constraints including the size, shape and controlaspects of a liquid meniscus lens have precluded their use in anophthalmic lens. Generally the cylindrical shape, sometimes referred toas the “hockey puck” shape of liquid meniscus lenses, has not beenconducive to something that can work in a human eye environment.

In addition, a curved liquid meniscus lens includes physical challengesthat are not necessarily present in a traditional design of a liquidmeniscus lens with parallel sidewalls and/or optical windows.

SUMMARY

Accordingly, the present invention provides a liquid meniscus lensincluding an arcuate front curve lens and an arcuate back curve lens.Included in the present invention is a meniscus wall with physicalfeatures conducive for one or both of attraction and repulsion of aliquid contained within the lens and forming a meniscus with anotherliquid.

According to the present invention, a first arcuate shaped optic isproximate to a second arcuate shaped optic with a cavity formedtherebetween. A saline solution and an oil are maintained within thecavity. Application of an electrostatic charge to a meniscus wallgenerally located in a perimeter area of one or both of the firstarcuate optic and the second arcuate optic changes the physical shape ofa meniscus formed between the saline solution and oil maintained withinthe cavity.

The present invention includes a meniscus wall formed into a compoundshape essentially including multiple convex segments, a cross-section ofwhich includes multiple torus segments in mechanical communication witheach other.

DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a prior art example of a cylindrical liquid meniscuslens in a first state.

FIG. 1B illustrates the prior art example of a cylindrical liquidmeniscus lens in a second state.

FIG. 2 illustrates a profile sliced cut away of an exemplary liquidmeniscus lens according to some embodiments of the present invention.

FIG. 3 illustrates a cross section of a portion of an exemplary arcuateliquid meniscus lens, according to some embodiments of the presentinvention.

FIG. 4 illustrates additional exemplary aspects of an arcuate liquidmeniscus lens.

FIG. 5 illustrates meniscus wall elements within an arcuate liquidmeniscus lens, according to some embodiments of the present invention.

FIG. 6A illustrates a multi-convex meniscus wall within a liquidmeniscus lens, showing the liquid meniscus boundary in its unpoweredstate.

FIG. 6B illustrates a multi-convex meniscus wall within a liquidmeniscus lens, showing the liquid meniscus boundary in its poweredstate.

FIG. 6C illustrates a multi-convex meniscus wall within a liquidmeniscus lens, showing the powered and unpowered states of the liquidmeniscus boundary in a single diagram for comparison.

FIG. 7A illustrates a cross-section of the multi-convex meniscus wallviewed separately from the rest of an arcuate liquid meniscus lens.

FIG. 7B illustrates a cross-section of one segment of the meniscus wallwhich is convex toward an optical axis formed in a lens, wherein aresulting a shape includes a segment of a torus when viewed separatelyfrom the rest of the arcuate liquid meniscus lens.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a liquid meniscus lens with at leastone of a front curve lens and a back curve lens defining a meniscuscavity of the liquid meniscus lens.

Glossary

In this description and claims directed to the presented invention,various terms may be used for which the following definitions willapply:

Contact Angle: The angle at which the oil/saline solution interface,also referred to as the liquid meniscus boundary, meets the meniscuswall. In the case of a linear meniscus wall, the contact angle ismeasured as the angle between the meniscus wall and the line tangent tothe liquid meniscus boundary at the point where the liquid meniscusboundary meets the meniscus wall. In the case of a curved meniscus wall,the contact angle is measured as the angle between the lines tangent tothe meniscus wall and the liquid meniscus boundary at the point wherethey meet.

Lens: As used herein, a Lens means an article with a front surface and aback surface that is optically transmissive to a predefined range ofwavelengths of radiation, such as, by way of example, visible light. Alens may include one or both of a front surface and a back surface whichare essentially flat or one or both of a front surface and a backsurface which are arcuate in shape.

Liquid Meniscus Boundary: The arcuate surface interface between thesaline solution and the oil. Generally, the surface will form a lensthat is concave on one side and convex on the other.

Meniscus Cavity: The space in an arcuate liquid meniscus lens betweenthe front curve lens and the back curve lens in which oil and salinesolution are maintained.

Meniscus Wall: A specific area on the interior of the front curve lens,such that it is within the meniscus cavity, along which the liquidmeniscus boundary moves.

Optical Zone: as used herein refers to an area of an ophthalmic lensthrough which a wearer of the ophthalmic lens sees.

Sharp: A geometric feature of an internal surface of either a frontcurve or back curve lens piece sufficient to contain the location of acontact line of two predefined fluids on the optic. The sharp is usuallyan outside corner rather than an inside corner. From a fluid standpointit is an angle greater than 180 degrees.

Referring now to FIG. 1A, a cut away view of a prior art lens 100 isillustrated with an oil 101 and a saline solution 102 contained withincylinder 110. The cylinder 110 includes two plates of optical material106. Each plate 106 includes an essentially flat interior surface113-114. The cylinder 110 includes an interior surface that isessentially rotationally symmetric. In some prior art embodiments, oneor more surfaces may include a hydrophobic coating. Electrodes 105 arealso included on or about the perimeter of the cylinder. An electricalinsulator may also be used proximate to the electrodes 105.

According to the prior art, each of the interior surfaces 113-114 isessentially flat or planar. An interface surface 112A is defined betweenthe saline solution 102A and the oil 101. As illustrated in FIG. 1A, theshape of the interface 112A is combined with the refractive indexproperties of the saline solution 102A and the oil 101 to receiveincident light 108 through a first interior surface 113 and providedivergent light 109 through a second interior surface 114. The shape ofthe interface surface between the oil 101 and the saline solution 102may be altered with the application of an electrical potential to theelectrodes 105.

FIG. 100A illustrates a perspective view of the prior art lensillustrated at 100.

Referring now to FIG. 1B, the prior art lens 100 is illustrated in anenergized state. The energized state is accomplished by applying voltage114 across the electrodes 115. The shape of the interface surface 112Bbetween the oil 101 and the saline solution 102B is altered with theapplication of an electrical potential to the electrodes 115. Asillustrated in FIG. 1B, incident light 108B passing through the oil 101and the saline solution 102B is focused into a convergent light pattern111.

Referring now to FIG. 2, a cut away view of a liquid meniscus lens 200with a front curve lens 201 and a back curve lens 202. In variousembodiments, the front curve lens 201 and the back curve lens 202 mayinclude an arcuate lens or a substantially flat lens. In some preferredembodiments, the front curve lens 201 and the back curve lens 202 arepositioned proximate to each other and form a cavity 210 therebetween.The front curve lens 201 includes a concave arcuate interior lenssurface 203 and a convex arcuate exterior lens surface 204. The concavearcuate interior lens surface 203 may have one or more coatings (notillustrated in FIG. 2). Coatings may include, for example, one or moreof electrically conductive materials or electrically insulatingmaterials, hydrophobic materials or hydrophilic materials. One or bothof the concave arcuate interior lens surface 203 and the coatings are inliquid and optical communication with an oil 208 contained within thecavity 210.

The back curve lens 202 includes a convex arcuate interior lens surface205 and a concave arcuate exterior lens surface 206. The convex arcuateinterior lens surface 205 may have one or more coatings (not illustratedin FIG. 2). Coatings may include, for example, one or more ofelectrically conductive materials or electrically insulating materials,hydrophobic materials or hydrophilic materials. At least one of theconvex arcuate interior lens surface 205 and the coatings are in liquidand optical communication with a saline solution 207 contained withinthe cavity 210. The saline solution 207 includes one or more salts orother components which are ionically conductive and as such may beeither attracted to or repulsed by an electric charge.

According to the present invention, an electrically conductive coating209 is located along at least a portion of a periphery of one or both ofthe front curve lens 201 and the back curve lens 202. The electricallyconductive coating 209 may include gold or silver and is preferablybiocompatible. Application of an electrical potential to theelectrically conductive coating 209 creates either an attraction or arepulsion of the ionically conductive salts or other components in thesaline solution 207.

The front curve lens 201 has an optical power in relation to lightpassing through the concave arcuate interior lens surface 203 and aconvex arcuate exterior lens surface 204. The optical power may be 0 ormay be a plus or minus power. In some preferred embodiments, the opticalpower is a power typically found in corrective contact lenses, such as,by way of non-limiting example, a power between −8.0 and +8.0 diopters.

The back curve lens 202 has an optical power in relation to lightpassing through the convex arcuate interior lens surface 205 and aconcave arcuate exterior lens surface 206. The optical power may be 0 ormay be a plus or minus power. In some embodiments, the optical power isa power typically found in corrective contact lenses, such as, by way ofnon-limiting example, a power between −8.0 and +8.0 diopters. An opticalaxis 212 is formed through the back curve lens 202 and the front curvelens 201.

Various embodiments may also include a change in optical powerassociated with a change in shape of a liquid meniscus 211 formedbetween the saline solution 207 and the oil 208. In some embodiments, achange in optical power may be relatively small, such as, for example, achange of between 0 to 2.0 diopters of change. In other embodiments, achange in optical power associated with a change in shape of a liquidmeniscus may be up to about 30 or more diopters of change. Generally, ahigher change in optical power associated with a change in shape of aliquid meniscus 211 is associated with a relatively increased lensthickness 213.

According to some embodiments of the present invention, such as thoseembodiments that may be included in an ophthalmic lens, such as acontact lens, a cross cut lens thickness 210 of an arcuate liquidmeniscus lens 200 will be up to about 1,000 microns thick. An exemplarylens thickness 210 of a relatively thinner lens 200 may be up to about200 microns thick. Preferred embodiments may include a liquid meniscuslens 200 with a lens thickness 210 of about 600 microns thick. Generallya cross cut thickness of front curve lens 201 may be between about 35microns to about 200 microns and a cross cut thickness of a back curvelens 202 may also be between about 35 microns and 200 microns.Typically, a cross-sectional profile includes a defined variance inthickness at different locations in the lens 200.

According to the present invention, an aggregate optical power is anaggregate of optical powers of the front curve lens 201 the back curvelens 202 and a liquid meniscus 211 formed between the oil 208 and thesaline solution 207. In some embodiments, an optical power of the lens200 will also include a difference in refractive index as between one ormore of the front curve lens 201, the back curve lens 202, the oil 208and the saline solution 207.

In those embodiments that include an arcuate liquid meniscus lens 200incorporated into a contact lens, it is additionally desirous for thesaline 207 and oil 208 to remain stable in their relative positionswithin the arcuate liquid meniscus lens 200 as a contact wearer moves.Generally, it is preferred to prevent the oil 208 from floating andmoving relative to the saline 207 when the wearer moves. Accordingly, anoil 208 and saline solution 207 combination is preferably selected witha same or similar density. Additionally, an oil 208 and a salinesolution 207 preferably have relatively low miscibility so that thesaline solution 207 and oil 208 will not mix.

In some preferred embodiments, a volume of saline solution 207 containedwithin the cavity 210 is greater than the volume of oil 208 containedwithin the cavity 210. Additionally, some preferred embodiments includethe saline solution 207 in contact with essentially an entirety of aninterior surface 205 of the back curve lens 202. Some embodiments mayinclude a volume of oil 208 that is about 66% or more by volume ascompared to an amount of saline solution 207. Some additionalembodiments may include an arcuate liquid meniscus lens wherein a volumeof oil 208 is about 90% or less by volume as compared to an amount ofsaline solution 207.

Referring now to FIG. 3, a cutaway of an edge portion of an arcuateliquid meniscus lens 300 is illustrated. As discussed above, an arcuateliquid meniscus lens 300 includes combined front curve lens 301 and backcurve lens 302 components. The front curve lens 301 and back curve lens302 may be formed with one or more materials that are at least partiallytransparent. In some embodiments, one or both of the front curve lens301 and the back curve lens 302 include generally optically clearplastic, such as for example, one or more of: PMMA, Zeonor and TPX.

One or both of the front curve lens 301 and the back curve lens 302 maybe fashioned, for example via processes such as one or more of: singlepoint diamond turning lathing; injection molding; digital mirror devicefree forming.

One or both of the front curve lens 301 and the back curve lens 302 mayinclude a conductive coating 303, as illustrated, the conductive coating303 extending along a perimeter portion from 309 to 310. In somepreferred embodiments, a conductive coating 303 includes gold. The goldmay be applied via a sputter process, vapor deposition or other knownprocess. Alternative conductive coating 303 may include, by way ofnon-limiting example, aluminum, nickel, and indium tin oxide. Generally,the conductive coating 303 will be applied to perimeter areas of one orboth of the front curve lens 301 and the back curve lens 302.

In some embodiments of the present invention, a back curve lens 302 hasa conductive coating 304 applied to specific areas. For example,portions about the perimeter of the back curve lens 302 may be coatedfrom a first boundary 304-1 to a second boundary 304-2. The goldcoatings may be applied for example via a sputter process or a vapordeposition. In some embodiments, a mask may be used to apply the gold orother conductive material in a predetermined pattern around one or moreperimeter portions of a front curve lens 301 or a back curve lens 302.Alternative conductive materials may be applied using various methodsand covering varying areas of the back curve lens 302.

In some embodiments, a conductive pass through, such as, for example oneor more holes or slots in a back curve lens 302 may be filled with aconductive filler material, such as, for example, a conductive epoxy.The conductive filler may provide electrical communication to aconductive coating on an interior surface of one or both of the frontcurve lens 301 and the back curve lens 302.

In another aspect of the present invention, one or both of the frontcurve lens 301 and the back curve lens 302 may be created from multipledifferent materials wherein an optical zone generally in a central areaof the front curve lens 301 and the back curve lens 302 (notillustrated) may include an optically transparent material and aperipheral zone may include an optically opaque area that includes anelectrically conductive material. The optically opaque area may alsoinclude one or more of control circuitry and energy sources.

In still another aspect, in some embodiments, an insulator coating 305is applied to a front curve lens 301. By way of non-limiting example,the insulator coating 305 may be applied in an area from a first region305-1 and extend to a second region 305-2. Insulators may include, forexample, Parylene C™, Teflon AF or other materials with variouselectrical and mechanical characteristics and electrical resistance.

In some specific embodiments, an insulator coating 305 creates aboundary area to maintain separation between the conductive coating 303and a saline solution 306 contained in a cavity between the front curvelens 301 and the back curve lens 302. Some embodiments accordinglyinclude an insulator coating 305 patterned and positioned in one or moreareas of one or both of the front curve lens 301 and the back curve lens302 to prevent a positively charged conductor 303 and negatively chargedsaline solution 306 from coming into contact, wherein contact of aconductor 303 and a saline solution 306 will result in an electricalshort circuit. Embodiments may include a positively charged salinesolution 306 and a negatively charged conductor 303.

Still other embodiments may allow for a short circuit between aconductor 303 and a saline solution 306 as a reset function of circuitryassociated with the operation of the lens 300.

For example, a short circuit condition may equalize potential applied tothe lens and cause the saline solution 306 and the oil 307 to revert toa default position.

Some preferred embodiments include a conductor 303 that extends from anarea 309 on the interior of the cavity 311 to an area 310 external tothe cavity 311. Other embodiments may include a channel 312 through thefront curve lens or the back curve lens which may be filled with aconductive material 313, such as, for example, a waterproof conductiveepoxy. The conductive material 313 may form or be connected to anelectrical terminal external to the cavity. An electrical potential maybe applied to the terminal and conducted to the coating via theconductive material 313 in the channel 312.

The thickness of the insulator coating 305 may be varied as a parameterof lens performance. According to the present invention, chargedcomponents, including the saline solution 306 and the conductor 303, aregenerally maintained on either side of the insulator coating 305. Thepresent invention provides for an indirect relationship between thethickness of the insulator coating 305 and an electrical field betweenthe saline solution 306 and the conductor 303, wherein the farther apartthe saline solution 306 and the conductor 303 are maintained, the weakerthe electrical field will be.

Generally, the present invention provides that electrical field strengthmay fall off dramatically as insulator coating 305 thickness increases.The closer together the fields are, the more energy that will generallybe available to move a spherical liquid meniscus boundary 308. As adistance between the saline solution 306 and conductor 303 increases,the farther apart electrostatic charges of the saline solution 306 andthe conductor coating 303 will be and therefore the harder it is to getthe spherical liquid meniscus boundary 308 to move. Inversely, thethinner the insulator coating 305, the more susceptible is the lens todefects in an insulator coating 305. Generally, even a relatively smallhole in the insulator coating 305 will create an electrical shortcircuit and the lens will not function in an electrowetting fashion.

In some embodiments, it is desirable to include a saline solution 306with density that is generally the same density of an oil 307 alsocontained within the lens 300. For example, a saline solution 306 maypreferably include a density that is within 10% of a density of an oil307 and more preferably the saline solution 306 will include a densitywithin 5% of a density of an oil and most preferably within about 1% orless. In some embodiments, a concentration of salts or other componentswithin the saline solution 306 may be adjusted to adjust the density ofthe saline solution 306.

According to the present invention, an arcuate liquid meniscus lens 300will provide a more stable optical quality by limiting movement of theoil 307 in relation to the front curve lens 301 and the back curve lens302. One method of maintaining stability of movement of the oil 307 inrelation to one or both of the arcuate front curve lens 301 and the backcurve lens 302 is to maintain a relatively congruent density in the oil307 and the saline solution 306. In addition, due to the curve design ofthe interior surfaces of both the front curve lens 301 and the backcurve lens 302, the relative depth or thickness of a layer of salinesolution 306 is diminished as compared to a traditional cylindrical lensdesign. In this scenario, the interfacial forces acting on fluids withinthe cavity may have a relatively greater contribution toward maintainingan unperturbed liquid meniscus boundary 308. Consequently, the densitymatching requirement may become more relaxed in such cases. In someembodiments, the relative thinness of the fluid layers further supportsthe liquid lens boundary 308.

In some preferred embodiments, the saline solution 306 provides a lowrefractive index as compared to the oil 307 which provides a relativelyhigh refractive index. However, in some embodiments it is possible toinclude a saline solution 306 with a higher refractive index as comparedto the oil 307 which in such cases provides a relatively lowerrefractive index.

An adhesive 314 may be used to secure the front curve lens 301 and backcurve lens 302 in place proximate to each other, thereby retaining theoil 307 and saline solution 306 therebetween. The adhesive 314 acts as aseal so that there is no leakage of saline solution 306 or oil 307 fromthe curved liquid meniscus lens 300.

Referring now to FIG. 4, a curved liquid meniscus lens 400 isillustrated with a liquid meniscus boundary 401 between the salinesolution 406 and oil 407. According to some preferred embodiments, ameniscus wall 405 is defined in the front curve lens 404 by a firstangular break in an arcuate wall extending between 402 and 403. Theliquid meniscus boundary 401 will move up and down the meniscus wall 405as electrical potential is applied and removed along one or moreconductive coatings or conductive materials 408.

In some preferred embodiments, a conductive coating 408 will extend froman area internal to the cavity 409 holding the saline solution 406 andthe oil 407 to an area external to the cavity 409 containing the salinesolution 406 and oil 407. In such embodiments, the conductive coating408 may be a conduit of an electrical potential applied to theconductive coating 408 at a point external to the cavity 409 to an areaof the conductive coating 408 within the cavity 409 and in contact withthe saline solution 406.

Referring now to FIG. 5, a cut away view of an edge portion of anarcuate liquid meniscus lens 500 is shown with a front curve lens 501and a back curve lens 502. The arcuate liquid meniscus lens 500 maycontain saline solution 503 and oil 504. The geometry of the arcuateliquid meniscus lens 500 and the characteristics of the saline solution503 and oil 504 facilitate formation of a liquid meniscus boundary 505between the saline solution 503 and oil 504.

Generally, a liquid meniscus lens may be viewed as a capacitor with oneor more of: conductive coatings, insulator coatings, pathways, andmaterials present on or through the front curve lens 501 and back curvelens 502. According to the present invention, a shape of a liquidmeniscus boundary 505 and therefore a contact angle between the liquidmeniscus boundary 505 and the front curve lens 501 change in response toan electrical potential applied to a surface of at least a portion ofone or both of the front curve lens 501 and the back curve lens 502.

According to the present invention, a change in an electrical potentialapplied to the saline solution 503 via the conductive coatings ormaterials changes a position of the liquid meniscus boundary 505 along ameniscus wall 506. The movement takes place between a first sharp 506-1and a second sharp 506-2.

In preferred embodiments, the liquid meniscus boundary 505 will be at ornear the first sharp 506-1 when a first magnitude of electricalpotential is applied to the lens, such as, for example, a voltage andcurrent correlating with an unpowered state or resting state.

Application of a second magnitude of electrical potential, sometimesreferred to as a first powered state, may correlate with a movement ofthe liquid meniscus boundary 505 along the meniscus wall 506 generallyin the direction of the second sharp 506-2, causing the shape of theliquid meniscus boundary to change. As discussed further below,according to the present invention, each of multiple sharps includedalong a meniscus wall may be associated with respective powered states.

An applied voltage for transitioning between a first powered state and asecond powered state may include, for example, a direct current voltageof between about 5 volts to about 60 volts. In other embodiments analternating current voltage may also be utilized.

In some embodiments, the meniscus wall 506 will be a smooth surface inrelation to the thickness of the insulator coating. A smooth meniscuswall 506 surface may minimize defects in the insulator coating.Additionally, because random irregularities in surface texture mayresult in uneven fluid motion and therefore cause uneven orunpredictable meniscus motion when energizing or de-energizing the lens,a smooth meniscus wall 506 is preferred. In some preferred embodiments,a smooth meniscus wall includes a peak to valley measurement along themeniscus wall 506 in the range of between about 1.25 nanometers to 5.00nanometers.

In another aspect, in some embodiments, it is desirable for the meniscuswall 506 to be hydrophobic, in which case a defined texture, such as anano-textured surface, may be incorporated in the design of the arcuateliquid meniscus lens.

In still another aspect, in some embodiments, the meniscus wall 506 maybe angled relative to an optical axis of the lens. The angle can rangefrom 0°, or parallel to the optical axis, to at or near 90°, orperpendicular to the optical axis. As illustrated, and in some preferredembodiments, the meniscus wall 506 angle is generally between about 30°and 50° in order for the arcuate liquid meniscus lens to function giventhe current contact angle between the liquid meniscus boundary 505 andthe insulator-coated meniscus wall 506. With the use of differentmaterials or with different optical objectives, such as telescopicvision, the angle of the meniscus wall 506 may be closer to 0° or 90°.

According to the present invention, an angle of a meniscus wall 506 maybe designed to accommodate a magnitude of movement along a meniscus wall506 upon application of a specified electrical voltage. In someembodiments, as meniscus wall 506 angle increases, the ability to changelens power generally decreases within given lens size and voltageparameters. Additionally, if the meniscus wall 506 is at or near 0°relative to the optical axis, the liquid meniscus boundary 505 will besteered nearly straight onto the front optic. Meniscus wall angle is oneof several parameters that can be tailored to provide various outcomesin lens performance.

In some preferred embodiments, the meniscus wall 506 is approximately0.265 mm in length. However, the angle of the meniscus wall 506 togetherwith the size of the overall lens will naturally affect meniscus wall506 length in various designs.

It may generally be considered that an arcuate liquid meniscus lens 500will fail if the oil 504 contacts the back curve lens 502. Therefore, inpreferred embodiments, the meniscus wall 506 is designed to allow aminimum clearance of 50 microns between the first sharp 506-1 and theback curve lens 502 at its nearest point. In other embodiments, theminimum clearance may be less than 50 microns, although the risk of lensfailure increases as the clearance is reduced. In yet other embodiments,the clearance may be increased to mitigate the risk of lens failure, butthe overall lens thickness will also increase which may be undesirable.

In still another aspect of some preferred embodiments of the presentinvention, the behavior of a liquid meniscus boundary 505 as it travelsalong a meniscus wall 506 may be extrapolated using Young's Equation.Although Young's Equation defines the balance of forces caused by a wetdrop on a dry surface and assumes a perfectly flat surface, thefundamental properties can be applied to the electrowetted lensenvironment created within the arcuate liquid meniscus lens 500.

A first magnitude of electrical energy may be applied to the lens, suchas, for example, when the lens is in an unpowered state. During theapplication of the first magnitude of electrical energy, a balance ofinterfacial energies between the oil 504 and saline solution 503 isachieved. Such a state may be referred to herein as a liquid meniscusboundary 505. The oil 504 and meniscus wall 506, and the saline solution503 and meniscus wall 506, form an equilibrium contact angle between theliquid meniscus boundary 505 and the meniscus wall 506. When a change inmagnitude of voltage is applied to the arcuate liquid meniscus lens 500,the balance of interfacial energies will change, resulting in acorresponding change in contact angle between the liquid meniscusboundary 505 and the meniscus wall 506.

The contact angle of the liquid meniscus boundary 505 with theinsulator-coated meniscus wall 506 is an important element in the designand function of the arcuate liquid meniscus lens 500 not only due to itsrole in the Young's Equation in movement of the liquid meniscus boundary505, but also because the contact angle is used in conjunction withother features of the arcuate liquid meniscus lens 500 to limit meniscusmovement.

Discontinuities, such as sharps 506-1 and 506-2, at both ends of themeniscus wall 506 act as boundaries for liquid meniscus 505 movementbecause it would require a significant change in applied electricalpotential to effect a large enough change in liquid meniscus contactangle to move the liquid meniscus boundary 505 past one of the sharps.By way of non-limiting example, in some embodiments, a contact angle ofthe liquid meniscus boundary 505 with the meniscus wall 506 is in therange of 15° to 40° whereas the contact angle of the liquid meniscusboundary 505 with the step 507 beyond the second sharp 506-2 is perhapsin the range of 90° to 130° and in some preferred embodiments about110°.

A voltage may be applied to the lens, resulting in movement of theliquid meniscus boundary 505 along the meniscus wall 506 toward thesecond sharp 506-2. The natural contact angle of the liquid meniscusboundary 505 with the insulator-coated meniscus wall 506 will cause theliquid meniscus boundary 505 to stop at the second sharp 506-2 unlesssignificantly more voltage is supplied.

At one end of the meniscus wall 506, a first sharp 506-1 generallydefines one limit beyond which the liquid meniscus boundary 505 will nottypically move. In some embodiments, the first sharp 506-1 isconstructed as a sharp edge. In other preferred embodiments, the firstsharp 506-1 has a defined small radial surface which can be created withless possibility of defect. Conductive, insulator, and other possibledesired coatings may not deposit evenly and predictably on a sharp edge,whereas a defined radius edge of the radial surface can be coated morereliably.

In some embodiments, the first sharp 506-1 is constructed at about a 90°angle with a defined radius of about 10 microns. The sharp may also becreated with less than a 90° angle. In some embodiments, a sharp with alarger angle than 90° may be used to increase the sturdiness of thesharp, but the design would then take up more lens space.

In various embodiments, a defined radius of a sharp 506-1 and/or 506-2may be in the range of 5 microns to 50 microns. A larger defined radiusmay be used to improve the reliability of the coatings, but at the costof using more space within the tight confines of the lens design. Inthis, as in many other areas of lens design, tradeoffs exist betweenease of construction, optimization of lens functions, and minimizingsize. A functional, reliable arcuate liquid meniscus lens 500 may bemade using a wide range of variables.

In some embodiments, a larger sharp radius may be used in conjunctionwith an improved surface finish on a side-wall between two adjacentsharps. In some embodiments, it may be desirable that a surface from afirst radius (sharp) to a second radius (sharp) be smooth and withoutdiscontinuities wherein it is helpful to cut a mold used to fashion asharp with the same tool. Radii included in a sharp may be cut into amold tool surface, wherein the mold tool surface radius is larger thanthe sharp radius. Wherein the mold tool surface is a continuous surfaceincluding one or more sharps and a side wall. A larger tool radius maygenerally relate to a smoother surface finish of a corresponding cut.

A second sharp 506-2, includes a feature designed to limit oil movementwhen voltage is applied to the arcuate liquid meniscus lens 500. Thesecond sharp 506-2 may also include, in some embodiments a generallypointed end, or in other embodiments, the second sharp 506-2 may includea defined radius of between 5 and 25 microns, most preferred 10 microns.A 10 micron radius performs well as a sharp and can be created usingsingle point diamond turning lathe or injection molding processes.

A vertical or nearly vertical step 507, extending to a start of theoptical area 508 of the front curve lens 501 may be included on a sideof the second sharp 506-2 opposing the meniscus wall 506. In someembodiments, the step 507 is 120 microns in height, although it could bein the range of 50 to 200 microns.

In some embodiments, the step 507 may be angled at about 5° from opticalaxis. In other embodiments, the step 507 angle may be as little as 1° or2° or may be angled more than 5°. A step 507 that is less angled fromoptical axis will generally act as a more effective limiter of meniscusmovement because it would require a greater change in the contact angleof the liquid meniscus boundary 505 to move off of the meniscus wall 506and onto the step 507. The transition from the step 507 to the start ofthe optical area 508 is a 25 micron radius. A larger radius wouldunnecessarily consume more space within the lens design. A smallerradius is possible and may be implemented if necessary to gain space.The decision to use a defined radius rather than a theoretical sharp inthis area as well as others in the lens is based, in part, on thepotential move to an injection molding process for lens elements. Acurve between the step 507 and the start of the optical area 508 willimprove plastic flow during the injection molding process and result ina lens with optimal strength and stress-handling characteristics.

Referring now to FIG. 6A, in some embodiments, a multi-convex meniscuswall 601 is depicted which may be included in a liquid meniscus lens.The multi-convex meniscus wall 601 includes multiple segments which areconvex in relation to an optical axis formed through the liquid meniscuslens. The multiple segments which are convex in relation to the opticalaxis may or may not be interspersed with segments of a meniscus wallthat include other shapes in relation to the optical axis, such as, forexample, a linear shape, a concave shape or a stepped shape. Othershaped features and segments may also be interspersed.

In some embodiments, a multi-convex meniscus wall 601 may be placed atapproximately a forty five degree (45°) angle from an optical axis in anarcuate liquid meniscus lens containing oil 602 and saline solution 603.In some embodiments, a liquid meniscus boundary 604A contacts themulti-convex meniscus wall 601 at 605A in a first state of potentialapplied to the multi-convex wall 601, such as, for example in anunpowered state. Generally, in some exemplary embodiments, the firstpowered state includes the liquid meniscus boundary near the end of themulti-convex meniscus wall 601 closest to the first sharp 607.

FIG. 6B depicts the location of a liquid meniscus boundary 604B in asecond powered state, such as a powered state with a voltage applied tothe meniscus wall 601. In relation to a first state, including anunpowered state, the liquid meniscus boundary 604B has moved generallytoward the front curve lens 606 along the multi-convex meniscus wall601. The powered state may also include a liquid meniscus boundary 604Bgenerally nearer to a discontinuity 609 between convex segments in themulti-convex meniscus wall 601.

Referring now to FIG. 7A, a perspective view of the multi-convexmeniscus wall 701 component of the arcuate liquid meniscus lens is shownseparately from other portions of an arcuate liquid meniscus lens. Inthe illustrated embodiments, a multi-convex meniscus wall 701 includesfour convex meniscus wall segments, 701-1 through 701-4. The convex wallsegments are generally convex in relation to an optical axis 703 throughthe lens. Other embodiments may include more or less convex meniscuswall segments 701-1 to 701-4. A number of wall segments may be basedupon, for example, a physical size of a liquid meniscus lens, a numberof set positions of meniscus the lens is anticipated to deploy, or otherconcerns.

The multi-convex meniscus wall 701 is of a consistent length between thefirst sharp 702-1 and the second sharp 702-2 around the entire lens.Depicted in FIG. 7B is a perspective view of one convex meniscus wallsegment 701-1, the shape of which comprises a segment of a torus.

In some embodiments, a multi-convex meniscus wall will includediscontinuities that are formed by one or more helical tool paths on themeniscus lens wall. For example, a lathe may be utilized to form anessentially spiral or helix pattern in a meniscus lens wall or in moldtooling utilized to form a meniscus lens wall.

FIG. 6C combines FIGS. 6A and 6B, showing the location of the liquidmeniscus boundary in both an unpowered 604A state and a powered 604Bstate. According to the present invention, a liquid meniscus lens with amulti-convex meniscus wall 601 placed at a given angle relative to theoptical axis, as shown in FIG. 6C, provides more consistent andrepeatable control over liquid meniscus movement resulting from theapplication of an electrical potential to a meniscus wall portion than aliquid meniscus lens with a linear meniscus wall placed at a similarangle relative to the optical axis. Examples of a lens including alinear meniscus wall is described in the U.S. Patent Application Ser.No. 61,359,548, filed Jun. 29, 2010 and entitled, “LENS WITH CONICALFRUSTUM MENISCUS WALL”, which is incorporated herein by reference.

In some preferred embodiments, a voltage is applied to a liquid meniscuswall and a corresponding liquid meniscus boundary moves along themulti-convex meniscus wall 601 toward the front curve lens 606.Discontinuities 609 between convex meniscus wall segments are functionalto slow and stop liquid meniscus movement at designated zones to achievespecific add power changes or other desirable liquid meniscus boundarymovement. As the liquid meniscus boundary travels along each convexsegment, it will be slowed and more easily stopped near eachdiscontinuity 609 due to changes in liquid meniscus boundary contactangle on either side of the discontinuity 609. According to the presentinvention, if the liquid meniscus boundary 604A-604B movement is stoppednear a discontinuity 609, the liquid meniscus boundary 604A-604B movesslightly to settle at a second sharp 608 side of a discontinuity 609 dueto a channel effect of the discontinuities 609 upon the liquid meniscusboundary 604A-604B.

In some embodiments, a net effect of the present invention includes apredictable, small contact angle hysteresis which helps to stabilize theposition of the liquid meniscus boundary in spite of small voltagefluctuations. Furthermore, oil droplets may be retained by the channelstructures when the position of the liquid meniscus boundary is causedto change by applied voltage. The oil droplets assist with retraction ofthe liquid meniscus boundary when the lens is de-energized, leading to afaster and more predictable recovery time.

While the invention has been described with reference to particularembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from thescope of the invention.

Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed as the best mode contemplated forcarrying out this invention, but that the invention will include allembodiments falling within the scope and spirit of the appended claims.

The invention claimed is:
 1. An optical lens comprising: a front lenscomprising a front lens exterior surface and a front lens interiorsurface; a back lens comprising a back lens interior surface and a backlens exterior surface, said back lens positioned proximate to said frontlens such that said front lens interior surface and said back lensinterior surface form a cavity therebetween; a volume of saline solutionand oil contained within the cavity formed between said front lensinterior surface and said back lens interior surface, said volume ofsaline solution and oil comprising a meniscus therebetween; and ameniscus wall comprising a general shape of multiple segments of atorus, each of said segments convex toward the optical axis formed inone or both of the front lens and back lens and bordering the meniscusformed between the saline solution and oil; and wherein at least one ofthe front lens and the back lens is essentially flat.
 2. The opticallens of claim 1 wherein the front lens and the back lens comprise anarcuate lens.
 3. The optical lens of claim 2 additionally comprising aconductive coating on at least a portion of said meniscus wall.
 4. Theoptical lens of claim 3 wherein the volume of oil comprises a densityabout equal to a density of the saline solution.
 5. The optical lens ofclaim 3 wherein the volume of oil comprises density within about 10% ofa density of the saline solution.
 6. The optical lens of claim 3 whereinthe volume of oil comprises density within about 5% of a density of thesaline solution.
 7. The optical lens of claim 3 wherein the conductivecoating extends from an area interior to the cavity to an area externalto the cavity.
 8. The optical lens of claim 7, wherein the area ofconductive coating external to the cavity forms an electrical terminalfor providing an electrical potential to the liquid meniscus lens. 9.The optical lens of claim 7 wherein the saline solution and the oil forma meniscus and an application of an electrical potential to the area ofconductive coating external to the cavity cause a change in position ofcontact of the meniscus along the meniscus wall.
 10. The optical lens ofclaim 7 wherein the electrical potential comprises a direct current. 11.The optical lens of claim 7 wherein the electrical potential comprisesbetween about 3.5 volts to about 7.5 volts.
 12. The optical lens ofclaim 7 wherein the electrical potential comprises between about 5.0volts to 60.0 volts.
 13. The optical lens of claim 12 wherein theelectrical potential comprises about 20.0 volts.
 14. The optical lens ofclaim 12 wherein the electrical potential comprises about 5.0 volts. 15.The optical lens of claim 3 wherein the volume of oil is less than thevolume of saline solution contained within the cavity.
 16. The opticallens of claim 15 wherein the volume of oil comprises about 66% orgreater than the volume of saline solution.
 17. The optical lens ofclaim 15 wherein the volume of oil comprises about 90% or less than thevolume of saline solution.
 18. The optical lens of claim 15 wherein thefront lens exterior surface comprises an optical power other than about0.
 19. The optical lens of claim 15 wherein the front lens interiorsurface comprises an optical power other than about
 0. 20. The opticallens of claim 15 wherein the back lens exterior surface comprises anoptical power other than about
 0. 21. The optical lens of claim 15wherein the back lens interior surface comprises an optical power otherthan about
 0. 22. The optical lens of claim 15 additionally comprising achannel through one or both of the front lens and the back lens and aconductive material filling the channel.
 23. The optical lens of claim22 additionally comprising a terminal in electrical communication withthe conductive material filling the channel.
 24. The optical lens ofclaim 23 wherein application of an electrical potential to the terminalcauses a change in the shape of the meniscus.
 25. The optical lens ofclaim 15 additionally comprising an insulator coating along at least aportion of the interior surface of the front lens, wherein the insulatorcoating comprises an electrical insulator.
 26. The optical lens of claim25, wherein the insulator comprises one of Parylene C™ and Teflon® AF.27. The optical lens of claim 25 wherein the insulator comprises aboundary area to maintain separation between the conductive coating anda saline solution contained in the cavity between the front lens and theback lens.
 28. An optical lens comprising: a front lens comprising afront lens exterior surface and a front lens interior surface; a backlens comprising a back lens interior surface and a back lens exteriorsurface, said back lens positioned proximate to said front lens suchthat said front lens interior surface and said back lens interiorsurface form a cavity therebetween; a volume of saline solution and oilcontained within the cavity formed between said front lens interiorsurface and said back lens interior surface, said volume of salinesolution and oil comprising a meniscus therebetween; a meniscus wallcomprising a general shape of multiple segments of a torus convex towardthe optical axis formed in one or both of the front lens and back lensand bordering the meniscus formed between the saline solution and oil;and a channel through one or both of the front lens and the back lensand a conductive material filling the channel.
 29. The optical lens ofclaim 28 wherein at least one of the front lens and the back lens isessentially flat.
 30. The optical lens of claim 28 additionallycomprising a terminal in electrical communication with the conductivematerial filling the channel.
 31. The optical lens of claim 30 whereinapplication of an electrical potential to the terminal causes a changein the shape of the meniscus.
 32. The optical lens of claim 28 whereinthe front lens and the back lens comprise an arcuate lens.
 33. Theoptical lens of claim 32 additionally comprising a conductive coating onat least a portion of said meniscus wall.
 34. The optical lens of claim33 wherein the volume of oil comprises a density about equal to adensity of the saline solution.
 35. The optical lens of claim 33 whereinthe volume of oil comprises density within about 10% of a density of thesaline solution.
 36. The optical lens of claim 33 wherein the volume ofoil comprises density within about 5% of a density of the salinesolution.
 37. The optical lens of claim 33 wherein the conductivecoating extends from an area interior to the cavity to an area externalto the cavity.
 38. The optical lens of claim 37, wherein the area ofconductive coating external to the cavity forms an electrical terminalfor providing an electrical potential to the liquid meniscus lens. 39.The optical lens of claim 37 wherein the saline solution and the oilform a meniscus and an application of an electrical potential to thearea of conductive coating external to the cavity cause a change inposition of contact of the meniscus along the meniscus wall.
 40. Theoptical lens of claim 37 wherein the electrical potential comprises adirect current.
 41. The optical lens of claim 37 wherein the electricalpotential comprises between about 3.5 volts to about 7.5 volts.
 42. Theoptical lens of claim 37 wherein the electrical potential comprisesbetween about 5.0 volts to 60.0 volts.
 43. The optical lens of claim 42wherein the electrical potential comprises about 5.0 volts.
 44. Theoptical lens of claim 42 wherein the electrical potential comprisesabout 20.0 volts.
 45. The optical lens of claim 33 wherein the volume ofoil is less than the volume of saline solution contained within thecavity.
 46. The optical lens of claim 45 wherein the volume of oilcomprises about 66% or greater than the volume of saline solution. 47.The optical lens of claim 45 wherein the volume of oil comprises about90% or less than the volume of saline solution.
 48. The optical lens ofclaim 45 wherein the front curve lens exterior surface comprises anoptical power other than about
 0. 49. The optical lens of claim 45wherein the front curve lens interior surface comprises an optical powerother than about
 0. 50. The optical lens of claim 45 wherein the backcurve lens exterior surface comprises an optical power other than about0.
 51. The optical lens of claim 45 wherein the back curve lens interiorsurface comprises an optical power other than about
 0. 52. The opticallens of claim 45 additionally comprising an insulator coating along atleast a portion of the interior surface of the front curve lens, whereinthe insulator coating comprises an electrical insulator.
 53. The opticallens of claim 52, wherein the insulator comprises one of Parylene C™ andTeflon® AF.
 54. The optical lens of claim 52 wherein the insulatorcomprises a boundary area to maintain separation between the conductivecoating and a saline solution contained in the cavity between the frontcurve lens and the back curve lens.